In recent years, many light emitting devices and illumination apparatuses have appeared in which a semiconductor light emitting element such as a light emitting diode (LED) or a semiconductor laser (laser diode; LD) is used as an excitation light source, and, fluorescence, which is generated by irradiating a light emitting portion including a phosphor with excitation light generated by the excitation light source, is used as illumination light.
A light source device disclosed in PTL 1 is an example of such a light emitting device of the related art. The light source device disclosed in PTL 1 includes a semiconductor laser, a collimator which collimates laser light from the semiconductor laser as parallel beams of light flux, a condenser which collects the laser light of the parallel beams of light flux from the collimator, and a phosphor which absorbs the laser light collected by the condenser and emits incoherent light as spontaneously emitted light. The light source device employs a configuration having a laser light reflection mirror so that coherent laser light does not leak out. In addition, in this light source device, incoherent light emitted from the phosphor is reflected in a specific direction by a visible light reflection mirror so as to become illumination light.
Further, a light source device disclosed in PTL 2 includes a semiconductor laser, an optical fiber which guides excitation light from the semiconductor laser, a wavelength conversion member (that is, a light emitting portion) which is optically connected to an emission end portion of the optical fiber and receives excitation light emitted from the emission end portion so as to emit beams of light flux with different wavelengths, and a holding member which holds the wavelength conversion member and light divergence means disposed on an optical path of the excitation light. In addition, a distance between the emission end portion of the optical fiber and the light divergence means such as a lens or the wavelength conversion member, or a range of an effective region of the light divergence means and the wavelength conversion member is optimized in order to increase use efficiency of excitation light and miniaturize an illumination light emission portion.
Further, PTL 3 discloses a light emitting device in which a GaN-based semiconductor laser which generates laser light (excitation light) with a wavelength of 450 nm is used as an excitation light source, and, a phosphor (light emitting portion), which is excited by the laser light from the excitation light source so as to generate fluorescence (non-excitation light) in a visible range, is combined with the excitation light source.